Once through boiler

ABSTRACT

An once through boiler characterized in that the drum has larger diameter pipes and smaller diameter pipes for water to be heated thereby pressure loss is generated in the smaller diameter pipes for preventing from unstable flow of the water.

United StateS'Patent 1 1 Kozeki Jan. 14, 1975 ONCE THROUGH BOILER 3,254,633 6/1966 Ammon ct al. 122 32 3,395,676 8/l968 S ra ue 122/32 [75] Invent lJvlmbum' 19ml, Yachlyosh 3,742,915 7/1973 riesliii 122/32 apan [73] Asslgnee: gg ij g ztx i f Primary Examiner-Kenneth W. Sprague p Attorney, Agent, or FirmHows0n and Howson [22] Filed: Oct. 15, 1973 [21] Appl. No.: 406,631 0 [57] 2 ABSTRACT 8" 122/32 An once through boiler characterized in that the drum [58] Fie'ld R 406 S has larger diameter pipes and smaller diameter pipes 122/406 for water to be heated thereby pressure loss is generated in the smaller diameter pipes for preventing from [56] References cued unstable flow of the water.

UNITED STATES PATENTS 1 Claim 3 Drawing Figures 3,ll2,735 12/1963 Schlichting et al. 122/32 i1 0 g ii 11 0 080:0 0 0 0 I 0 0 0 I o o o 1 0 O 1 o o o 1 o O o 1 O 0 0 ooo 0 0 0 0 o o o 0 O O l 1 o o o 0 0 0 16 3080801 1 ONCE THROUGHBOILER The present invention relates to a helical coil type once through boiler.

The most difficult problem with the helical coil once through boilers widely used is unstable flow of the fluid to be heated. In order to solve the problem, heretofore orifices as a resister are provided in the inlet portion for equilibrating flow rates. This method, however, still has the problems that the mechanism of the orifice portion is complicated and that when partial load rises somewhat, there still arises unstable flow pattern.

The present invention has for its object to provide an once through boiler wherein flow of the fluid to be heated is stable over a wide range of load.

Now, the present invention will be described in detail with reference to the accompanying drawings; in which,

FIG. 1 is a sectional view of a helical coil type once through boiler according to the present invention;

FIG. 2 is a sectional view taken along the line II-II of FIG. 1; and

FIG. 3 is a view showing the connection of one pipe line in the passage of the fluid to be heated.

Referring to FIGS. 1 and 2, reference numeral 1 designates a cylindrical drum having at its top end an inlet nozzle 2 of heating fluid and at the bottom an outlet nozzle 3. In the drum 1 are provided concentric cylindrical partition walls 11, 12, 13 at lower half of the drum, whereby there are defined, a downcommer chamber 10, a helical coil chamber 9 and a central space 4. A shield film 20 is provided between the top end of the partition wall 11 and the inside of the drum 1. A plurality of water supply pipes 8 are connected to a pipe header 5 provided in the upper portion of the drum 1. These water supply pipes 8 are connected to the downcommer pipes 16 disposed circumferentially in the chamber 10 respectively, and each downcommer pipe is connected at the bottom end to the connecting pipe 17. Disposed in the chamber 9 are a plurality of helical coil pipes 14 each of which lower end connected to the connecting pipe 17 through a reducer 15. Each helical coil pipe 14 is connected at the upper end to the respective vapor discharge conduit 7 and thereby connected to a header 6 provided at the upper part of the drum 1. Water supply pipes 8, downcommer pipes 16 and connecting pipes 17 are smaller in diameter than the helical pipes 14 and vapor conduits 7 so that a pressure loss will be generated. In the present embodiment, a cover 18 is mounted over the central space 4 to prevent bypassing of the heated fluid. This central space 4 can be utilized for various purposes.

In operation, heating fluid is introduced into the drum 1 from the inlet nozzle 2, a part of the fluid flowing through the downcommer chamber 10 and the remainder through the helical pipe channel 9, and after transmitting sensible heat of the heating fluid to the fluid to be heated, the heating fluid flows out from the outlet nozzle 3. On the other hand, the fluid to be heated is introduced in the conduits 8, and flows in the downcommer l6, connecting pipes 17, helical pipes 14 and vapor conduits 7, and flows out from the header 6. In the downcommers l6, preheating of water is taken place, while boiling and overheating are effected in the helical pipes 14. The downcommer pipes 16, connecting pipes 17 and water supply pipes 8 are formed smaller in diameter than the helical pipes 14, and flow resistance on the water supply side, which has been increased by orifices in the conventional systems, is increased by these small diameter pipes, and also heating fluid is flown through the downcommer 10 to effectuate heat transmission in these portions, too, thereby making it possible to use these portions as water preheating sections during heavy loading and to effect boiling in these portions, too, during small loading. Thus, the tendency of increasing the unstable flow due to elongation of the superheater tubes at the helical pipes 14 is alleviated.

According to the present invention, the mechanism can be more simplified than the conventional systems and also fluid flow can be stabilized over a wide range of load. Further, as the small diameter downcommer pipes are utilized for heating of water supplied, the boiler body can be reduced in size.

What is claimed is:

1. A once-through boiler, comprising drum means having heating fluid inlet means and heating fluid outlet means, a downcomer chamber and a helical coil chamber both insaid drum means and one within the other, a plurality of downcomer pipes in said downcomer chamber, means for supplying water to the upper ends of said downcomer pipes, a plurality of helical coil pipes in said helical coil chamber, each of said helical coil pipes being supplied at its lower end with water from the lower end of one of said downcomer pipes, said downcomer pipes and said helical coil pipes both being positioned in heat-exchange relation to said heating fluid as it passes from said inlet means to said outlet means, each of said downcomer pipes being substantially smaller in diameter than the helical coil pipe which it supplies.

t 6 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 59 9 4 DATED January 14, 1975 INVENTOR(S) i Moribumi Kozeki It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the first or Abstract page, below [211 Appl. N00:

406,631, add Q [30] Foreign Application Priority Data Oct 16, 1972 Japan 119795 e Signed and Sealed this ninth Of September 1975 [SEAL] Arrest.

RUTH c. MASON c. MARSHALL DANN Arresting Officer Commissioner of Parents and Trademarks 

1. A once-through boiler, comprising drum means having heating fluid inlet means and heating fluid outlet means, a downcomer chamber and a helical coil chamber both in said drum means and one within the other, a plurality of downcomer pipes in said downcomer chamber, means for supplying water to the upper ends of said downcomer pipes, a plurality of helical coil pipes in said helical coil chamber, each of said helical coil pipes being supplied at its lower end with water from the lower end of one of said downcomer pipes, said downcomer pipes and said helical coil pipes both being positioned in heat-exchange relation to said heating fluid as it passes from said inlet means to said outlet means, each of said downcomer pipes being substantially smaller in diameter than the helical coil pipe which it supplies. 